Tony Nicklinson, the locked-in syndrome sufferer who lost his High Court battle for the legal right to end his life when he chooses with a doctor's help, died on Wednesday.
In a brief statement, Bindmans LLP said the 58-year-old, from Melksham, Trowbridge, died at home on Wednesday morning.
The law firm has asked for his family's privacy to be respected.
His family has said that he died peacefully at home at 10am following a rapid deterioration in health after contracting pneumonia.
Mr Nicklinson was left paralysed by a catastrophic stroke while on a business trip to Greece in 2005.
A Wiltshire Police spokesman said the force would not be investigating Mr Nicklinson's death.
"Police are not involved at all. We can confirm he passed away and it is not a matter for Wiltshire Police," he said.
"His death certificate has been signed by a doctor, so it is not a matter for Wiltshire Police or the coroner."